Math

QuestionEvaluate the integral 0π/6sintcos2tdt\int_{0}^{\pi / 6} \frac{\sin t}{\cos ^{2} t} d t.

Studdy Solution

STEP 1

Assumptions1. We are asked to evaluate the definite integral 0π/6sintcostdt\int_{0}^{\pi /6} \frac{\sin t}{\cos ^{} t} d t . We know the integral and trigonometric identities

STEP 2

The integral can be simplified by using a substitution. We can let u=costu = \cos t, so du=sintdtdu = -\sin t\, dt.
sintcos2tdt=1u2du\int \frac{\sin t}{\cos ^{2} t} d t = -\int \frac{1}{u^{2}} du

STEP 3

Now, we can evaluate the integral using the power rule for integration, which states that xndx=1n+1xn+1\int x^n dx = \frac{1}{n+1}x^{n+1}.
1u2du=u2du=11+1u1+1=u1-\int \frac{1}{u^{2}} du = -\int u^{-2} du = \frac{1}{-1+1}u^{-1+1} = u^{-1}

STEP 4

Substitute u=costu = \cos t back into the integral.
u1=1costu^{-1} = \frac{1}{\cos t}

STEP 5

Now we need to evaluate the definite integral from 00 to π/\pi /. To do this, we substitute these values into the integral.
[1cost]0π/=1cos(π/)1cos(0)\left[\frac{1}{\cos t}\right]_{0}^{\pi /} = \frac{1}{\cos(\pi /)} - \frac{1}{\cos(0)}

STEP 6

Evaluate the cosine values.
1cos(π/6)1cos(0)=13/211\frac{1}{\cos(\pi /6)} - \frac{1}{\cos(0)} = \frac{1}{\sqrt{3}/2} - \frac{1}{1}

STEP 7

implify the fractions.
13/211=231\frac{1}{\sqrt{3}/2} - \frac{1}{1} =2\sqrt{3} -1So, the solution to the integral 0π/6sintcos2tdt\int_{0}^{\pi /6} \frac{\sin t}{\cos ^{2} t} d t is 2312\sqrt{3} -1.

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